AX2009 AIF Custom Service Schema Error

After creating an AXD custom query and running the AIF wizard I received the following error in the list of services:

SchemaError: The base type of the method parmItemId is different to the corresponding field...

I realised that the newly created Ax<Table>_InventBatch class was missing the ItemId methods: existsItemId and parmItemId.  Copying these from an existing class and Refreshing (Actualizar, in the image above) the service list was sufficient to remove the schema error.